1. Field of the Invention
This invention relates to an optical measuring device, an optical measuring apparatus and a fine particle measuring apparatus which uses an optical measuring device.
2. Description of the Related Art
In the past, apparatus are known which introduce fluid dispersion of fine particles such as living body-related fine particles such as cells, microorganisms and ribosome, latex particles or gel articles and synthetic particles such as industrial particles into a microfluidic channel and optically measure the fine particles introduced in the microfluidic channel in order to discriminate the fine particles.
One of such apparatuses is a particle analyzer which discriminates various synthetic particles depending upon the size and/or the shape of the same. The particle analyzer excites fine particles one by one in helium plasma so as to emit light to carry out spectral detection thereby to carry out measurement of the element composition, particle size and particle number of the fine particles.
Further, for living-body related fine particles, optical measurement using a flow cytometry or flow cytometer is used popularly as disclosed, for example, in Hiromitsu NAKAUCHI, “Cellular Engineering Separate Volume, Experiment Protocol Series, Master Flow Cytometry,” Shujunsha, the second edition, Aug. 31, 2006. According to the flow cytometry, fine particles such as cells or micro beads are flowed to the center of laminar flow of sheath liquid in a flow cell and measuring light is irradiated upon the fine particles in an optical detection section to detect scattered light or fluorescent light generated from the fine particles thereby to measure the size, structure and so forth of the fine particles.
The flow cytometry is configured so as to only measure the size, structure and so forth of fine particles or configured such that it can dispense desired fine particles based on the measured size, structure and so forth. Of such flow cytometries, that flow cytometry which dispenses cells is called “cell sorter.” Cell sorters on the market are manufactured by Beckman Coulter, Inc., Becton, Dickinson and Company or DAKO S/A. With those cell sorters, high-speed measurement and dispense of several tens to hundred thousand cells per second can be carried out.
In recent years, such optical measuring apparatus for fine particles are demanded to have a further enhancement measurement process speed and further enhanced measurement accuracy. Particularly for a cell sorter described above, it is demanded to have a processing speed and a measurement accuracy for efficiently isolating stem cells, which exist only little among living body cells, in response to rise of expectations for regenerative medicine.
In connection with the invention disclosed herein, a configuration of an existing cell sorter is shown in FIGS. 7 and 8 of Japanese Patent Laid-Open No. 2007-46947 (hereinafter referred to as Patent Document 1). The cell sorter includes a fluid or flow system for arraying cells colored with fluorescence-labeled reagent into a line in a flow cell, and an optical system for irradiating a plurality of Laser beams to detect detection target light such as scattered light and fluorescent light. The optical system of the existing flow cytometer is configured such that a plurality of measuring light beams from a plurality of light sources are condensed at different positions of the flow cell which forms a single microfluidic channel (refer to the FIG. 7 of Patent Document 1).
Meanwhile, Japanese Patent Laid-Open No. Hei 7-24309 (hereinafter referred to as Patent Document 2) discloses an apparatus for separation of particles, which includes a microfluidic channel along which particles move and a section for irradiating scanning light upon the microfluidic channel such that acting force corresponding to the type of particles is applied by the irradiation to carry out separation of the particles. While this apparatus has a configuration for scanning the scanning light on the flow cell, this scanning light is used for laser trapping of particles (refer to paragraph 0004 and so forth of Patent Document 2). It is to be noted that also this apparatus has a single configuration of the flow cell serving as a microfluidic channel.
Also a technique of forming fine microfluidic channels on a substrate of glass or a high-molecular material and flowing fine particles such as cells on water streams in the fine microfluidic channels to carry out flow cytometry to separate desired fine particles, which is a technique which utilizes a microchip, has been proposed. The technique is disclosed, for example, in Anne Y. Fu, et al., “A microfabricated fluorescence-activated cell sorter,” Nature Biotechnology, Vol. 17, November 1999, pp. 1109-111; or in Anne Y. Fu, et al., “An Integrated Microfabricated Cell Sorter,” Analytical Chemistry, Vol. 74, No. 11, Jun. 1, 2002, pp. 2451-2457. The microchip forms T-shaped microfluidic channels and isolates cells to be dispensed and the other cells from each other by changing over the flowing direction of sheath liquid, that is, by microfluidic channel selection control.